In 2006, Sales developed a water treatment device known as a high density bioreactor. It can cultivate activated sludge, which is used to remove oxygen organic carbon compounds from wastewater.

“Since then, Sales and his lab at Drexel have added algae to the mix to improve the reactor's nitrogen-removal capabilities and allow for the recovery of a potentially valuable resource: algal biomass,” the university said in a statement.

Why does it matter? The university says the new technique could be quicker than current nitrogen-removal processes, which sometimes require time for nitrogen-removing bacteria to settle out of the water. This technique may also simplify current processes, which often include multiple steps and require water be pushed through various tanks.

Sales said in a statement: “The process of nitrification requires a significant amount of energy because the tanks of nitrifying bacteria need to be constantly aerated to provide oxygen to drive the conversion of ammonium to nitrate. Similarly, wastewater treatment plants often need to add chemicals, such as methanol, to provide denitryfing bacteria with enough food to transform the nitrate from the nitrification process into nitrogen gas.”

What does the new technique look like?

“Sales’s bioreactor works by continuously cycling water into an algae and bacteria-laden environment, removing nitrogen by storing it in algae that can be easily separated from water in their new reactor. His data indicate that it can remove up to 80 percent of nitrogen from a waste stream,” the university explained.

“In addition, Sales’s system does not require a separate settling tank because the flow of the reactor is designed to naturally promote settling of biomass. This separation, Sales speculates, could one day make the algae cultivated in these bioreactors an appealing source of biofuel feedstock because it wouldn’t require as much energy to dry out as pond-grown algae,” it continued.